Question

I’m developing an iPhone Skype like application and I’m facing a “problem”.

I receive events for contacts that go online or offline but I don’t know when those updates will start or end.
I know that normally a connection event will come not more than 0.2 second after the previous event. And anyway if it come later, I don’t really care.

When I have all the events grouped I update my tableview to show the new status of contacts.
(I was previously updating my tableview as soon as I receive a connection event, but now that I start working with lot of contacts this is not any more suitable)

Given the missing start/end update information I set up a timer based check system that do as follow:

- (void)connectionStatusEventReceivedForContact:(Contact *)aContact {
    if (!isUpdating) {
        [self willStartToUpdateContacts];
    }
    newUpdateReceived = TRUE;

    NSIndexPath *indexPathToUpdate = [delegate indexPathOfContact:aContact];
    if (indexPathToUpdate != nil  && ![indexPathsOfContactToUpdate containsObject:indexPathToUpdate]) {
        [indexPathsOfContactToUpdate addObject:indexPathToUpdate];
    }
    [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(newUpdateReceived:) userInfo:nil repeats:NO];
}

- (void)willStartToUpdateContacts {
    isUpdating = TRUE;
}

- (void)newUpdateReceived:(id)sender {
    [self isLastUpdate:nil];
    [NSTimer scheduledTimerWithTimeInterval:0.6 target:self selector:@selector(updateNewUpdateBoolean:) userInfo:nil repeats:NO];
}

- (void)updateNewUpdateBoolean:(id)sender {
    newUpdateReceived = FALSE;
    lastUpdateTimer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(isLastUpdate:) userInfo:nil repeats:NO];
}

- (void)isLastUpdate:(id)sender {
    if (!newUpdateReceived) {
        [self didUpdateContacts];
    }
    newUpdateReceived = TRUE;
}

As you can see is a bit tricky, my concern is that when I have 500 contact, 1001 timer are scheduled. And that’s not really a good solution. I’m thinking how I can do this, but have not yet found a solution that I really like.
I’m sure that someone of you will help me to find a better solution 😀

Thank you guys

Answer 1

Perhaps you could queue up any notifications you receive and have a single timer that runs (perhaps every couple seconds) and updates any/all notifications received since that last time it fired.

That way you will get fairly good responsiveness using a single timer.